Many radios, especially radios found in cars and other vehicles, include one or more sub-circuits to facilitate the easy tuning of radio's receiver to a station that broadcasts the type of program the listener wants to hear. Some radios employ scanners which automatically scan the airwaves until they pick up signals of a preestablished minimum strength. The received signal is then played so as to give the listener the opportunity to evaluate whether or not he wants to listen to the broadcast program. If the listener does not want to the listen to the broadcast program, he reactivates the scanning circuit so that it locates a new signal which is then played. This process is repeated until the listener locates a broadcast station that is transmitting a program he wants to hear. Car radios can also be programmed with the broadcast frequencies of a number of different broadcast stations. This allows the listener to automatically tune the radio to the station he wants to listen to without having to first scan the broadcast frequency spectrum.
Some station programmable radios include a number of selection buttons equal to the number of stations to which the radio can be programmed. Other programmable radios include a single selection button and a display are provided, and in which the preset broadcasting station codes (or broadcasting station names) are displayed on the display by continuously pressing the selection button. With these radios, when the desired broadcasting station code is displayed the listener starts the reception operation by pressing a reception start button.
These latter programmable radio receivers include radios in which the broadcasting station frequencies are fixedly set, as in radio receivers used in countries with few broadcasting stations (for example, Japan). Programmable radios have also been provided employing a system in which the listener can preset the broadcast frequencies of desired broadcasting stations. These radios are typically used in countries in which there are a large number of broadcasting stations (for example, America).
Listener programmable radios are often supplied with a scanning circuit. This allows the listener to scan the broadcast frequency spectrum by pressing a search key which is provided on the radio receiver, scanning is halted at received frequencies of a fixed strength. The listener then selects whether or not to program the broadcast frequency, and desired broadcast frequencies are successively selected and recorded in a preset memory. Then, in order to receive a broadcast, the listener selects a desired broadcast station from amongst the programmed stations, and starts the reception operation, by continuously pressing a selection button.
In North American radio broadcasting stations, the type of program which is broadcast (for example music programs such as jazz, or news) is fixed for each broadcasting station. There are receivers which are configured such that data indicating which type of broadcast a particular broadcasting station performs is held in a database (specifically, the frequency, type of radio station, and a type indicator name, for example, are stored in a memory device such as a ROM or a PROM.) Based on this, the broadcast frequencies of desired broadcasting stations are recorded in a preset memory, and when a program is to be received, the desired program is received by successively reading them out (refer to Japanese Laid-open Patent Number H1-117529 ("broadcast receiver")).
In the conventional broadcasting receiver disclosed in the above mentioned Japanese Laid-open Patent Number H1-117529 (referred to as a receiver with an ID-LOGIC function), not only does the above mentioned database contain data consisting of the broadcasting frequency and the type, but also regional information indicating the geographic location of the broadcasting station is held as data. This information, the geographic location of the broadcast station, is important because in some parts of the world, such as in North America, there are a large number of broadcasting stations which have the same frequency. Accordingly, the data for the broadcast stations is first grouped by state or province, and then divided into broadcasting stations within a state or province. It should be noted that examples of ID-logic types include classical, jazz, public, country, news and/or talk radio.
Next, in describing an example of the operation of the above mentioned ID-logic function, (1) the listener specifies the point at which he is located (data for the state in which one is located is input, and then data for the city which has the broadcasting station one wishes to listen to is input (in America, for example, there are many cases in which broadcasting stations have been established concentrated in particular cities, and therefore there is no certainty that there will be a broadcasting station in the city which includes the current position of the listener (receiver). In such cases, the listener selects from a map the city which is nearest to the city in which the listener (receiver) is currently located, and sets this)). e.g., state selection: Nevada; city selection: Las Vegas (2) After completing selection of the state and the city, the listener performs the reception operation instruction by pressing a reception key, and the data corresponding to the reception frequency of the broadcasting station are retrieved from the ROM and the type is displayed. e.g., reception frequency: 87.9 MHz, type: popular music In addition, the ID-logic function can also search the broadcasting stations by type, using the database.
With radio receivers which perform type searching using the above mentioned ID-logic function, the listener must first specify the current position (of the receiver), and it is necessary to refer to a map, and input city (region) data. Although it is troublesome to input such city (region) data whilst looking at a map, the operation to set the city data is not particularly troublesome if the position of the receiver is fixed, or is within the reception area of the specified broadcasting station, in cases in which the position of the receiver is variable.
However, if consideration is given to a radio receiver installed in a vehicle, distances covered by the vehicle are great, particularly in countries such as America which have a car-based society. Thus there are many cases in which the reception area of broadcast radio waves of the specified broadcasting station is exceeded, and in some cases it is necessary to reset the city data frequently.
When vacationing in a car, for example, if a desired type of radio broadcast is being listened to using the ID-logic function, then the vehicle will become separated from the position of the initially specified broadcasting station, due to the movement of the vehicle. As the limit of reception of the broadcast radio waves is approached, it will become impossible to receive the broadcast radio waves, and the listener will perform a seek operation (radio wave search operation to receive broadcast radio waves) in order to listen to the desired type of broadcast, with the intention of listening to a corresponding type of broadcast which can be received. But, even if the receiver is tuned to the frequency of the type of broadcast which the listener wishes to receive, there is the problem that the city data (in other words the broadcasting station) will be different. It will thus be impossible to listen to the corresponding type of broadcast, and in order to listen to the corresponding type of broadcast it will be necessary to set the new city data (in other words the data for the nearest city in which the desired type of broadcasting station has been established, in the region through which the vehicle is currently passing).
In order to solve the above mentioned problem, the current position is corrected by the ID-logic function at fixed time intervals or fixed distances. In this case the correction is performed using, for example, direction keys indicating the direction in which one is currently moving from the initially set position (keys provided on the receiver indicating N (north), S (south), E (east) W (west).
However, radio receivers are not the only sound sources (sound systems) installed in vehicles, and CDs and cassette tape devices are also installed. Thus the listener will not always listen continuously to radio programs only, but may listen to a program, occasionally listen to music or the like recorded on a CD or cassette tape, and then return to the radio program.
Thus if, for example, the vehicle is started from the initially set position (without a radio broadcast being listened to) whilst the listener is listening to music or the like recorded on a CD, and then the listener operates the ID-logic function in order to listen to a radio program after the vehicle has traveled for some time, there is the problem that, since the set position and the current position are different, the ID-logic function does not function correctly. Further, there is the problem that the current position after traveling is not adjacent to the initially input position. Thus even if direction key operation is performed in order to correct the position, as described above, it is not possible to correct the position.
In such cases there is the inconvenience that it is necessary to reset the position information (city, region data) whilst looking at a map. Moreover, if there is no map, it may not be possible to set the information appropriately.